On Jul 2, 7:16 pm, Michael Ash wrote:
Ian wrote:
What you're forgetting - or perhaps what nobody told you - is that
it's the motion of the centre of pressure which really matters.
Basically, as the AOA increases the net lift force on the wing appears
to move forwards, and as the AOA decreases it moves back.

Much as I may want to blame this on others, it's likely that I just forgot
about it, or never managed to think of it.

This is unstable, since - all other things being equal: nose up -
increased AOA - cop moves forwards - nose up moment - nose up. So
what you do is stick a tail on the back. Now nose up - positive AOA
on tail - lift at tail and, if you get the sums and moment arms
right, this balances the pitching moment caused by the cop moving
forwards.

Now it all makes so much more sense.

As you'll have guessed, this is an enthusiasm of mine. I think a lot
of people would fly better, and find it easier, if they understood the
physics better. I include instructors, I'm afraid - hardly any of them
know why you need back stick in a turn, for example.

I agree that the more you know the better off you are in this regard.
Thanks to you, I'm now better off than I was before!

--
Michael Ash
Rogue Amoeba Software

O'K guys...what happen to the original thread about new sailplane? I
thought I posted a little info about the SZD 54-2 Perkoz and we ended
up where?

Jacek
Washington State